London 2012 chief Lord Coe says Dwain Chambers' decision to challenge his lifetime Olympic ban in court is damaging the image of athletics.

Chambers has served a two-year ban after testing positive for steroid THG.

But the 30-year-old is challenging his lifetime ban from the Olympics in the High Court next week.

"The risk is the efforts of 99% of athletes are overshadowed by the notoriety of Dwain and other drug users," Coe told the BBC.